With the ever increasing concern over fossil fuel supply, which has traditionally been the feedstock to produce a diverse range of goods including fuels, polymers, organic solvents, and even pharmaceutical compounds, research and development of biomass-based alternatives for fuels and commodity chemicals has gained significant attention. In the course of developing biomass-based alternatives, raw biomass is processed to a number of intermediates. 5-hydroxymethylfurfural (HMF) is one such intermediate that has been the subject of considerable attention. HMF is produced by dehydration of hexoses, such as glucose in cellulosic matter. Among the many reactions HMF may undergo (e.g. oxidation, reduction, etherification), reductive amination, which adds an amine group to a hydrocarbon framework, enables the synthesis of more diverse biomass-driven compounds including amine-based polymers (nylon) and pharmaceutical compounds.
Reductive amination of furfurals involves the conversion of the formyl group to an amine group, which is commonly accomplished in two steps as illustrated in Scheme 1. In this scheme the aldehyde is first converted to an aldimine (Step 1 in Scheme 1) by reaction with ammonia or a primary amine. Formation of the aldimine has traditionally utilized concentrated or liquid amine source and nonaqueous solvents. However, aldimine can also be formed in aqueous media under pH conditions where a large portion of ammonia or amine is present in its unprotonated form. The stability of aldimine is pH dependent and lowering pH can cause the hydrolysis of the aldimine back to aldehyde.

The second step of reductive amination is reduction of the aldimine to an amine by the hydrogenation of the C═N bond (Step 2 in Scheme 1). This process has commonly been achieved by using H2 over Raney Ni or precious metal catalysts (e.g. Au, Ir, Pd, Pt, Rh, and Ru). Recent efforts have been made to utilize inexpensive alternatives, such as FeNi alloy catalysts. However, for this method H2, which is a valuable fuel that must be generated from other primary energy sources, needs to be consumed. Hydrogenation can also be achieved by using a hydride (e.g., sodium borohydride, sodium cyanoborohydride, and sodium triacetoxyborohydride) or by using Zn powder as a reducing agent and water as the hydrogen source. These reactions, however, require the consumption of reducing agents, significant solution cleanup, and disposal of waste that can be toxic.